Field of the Invention
The present invention relates to a battery pack, and particularly to a battery remaining power predicting device which predicts a battery remaining power of a lithium ion rechargeable battery or the like.
Background Art
A charging battery has been used in a number of devices, starting with a portable device. A battery management system for managing charging/discharging is essential therefor. It is particularly necessary to more accurately recognize the operation time of the charging battery during the device operation. To this end, a battery remaining power predicting device has been used.
A battery pack equipped with a related art battery remaining power predicting device is illustrated in FIG. 7. The related art battery remaining power predicting device 20 is equipped with a CPU 21 which performs a signal processing computation, a RAM 22 used upon the signal processing computation, an ADC 23 for detecting a battery voltage obtained by converting a battery voltage corresponding to one cell of a charging battery 7 by a level translator 26, an ADC 24 for detecting a voltage developed across a current sense resistor 6 for detecting a current of the charging battery 7, and a nonvolatile-memory 25 which holds characteristic data of the charging battery, etc. therein in advance. The battery remaining power predicting device determines the battery remaining power from the voltage of the charging battery 7, a moving charge quantity determined by a coulomb counter from the current value of the charging battery 7 measured using the current sense resistor 6, etc. The high accuracy measurement of the voltage and current of the charging battery 7 is essential for a highly accurate remaining power prediction.
Paying particular attention to the current measurement, there is a demand for the current sense resistor 6 to have a highly accurate resistance value.
[Patent Document 1] U.S. Pat. No. 6,789,026 Specification
[Patent Document 2] U.S. Pat. No. 6,832,171 Specification